Specific serum antibody responses following a Toxoplasma gondii and Trichinella spiralis co-infection in swine.

The aim of this study was to examine the dynamics of parasite specific antibody development in Trichinella spiralis and Toxoplasma gondii co-infections in pigs and to compare these with antibody dynamics in T. spiralis and T. gondii single infections. In this experiment, fifty-four pigs were divided into five inoculated groups of ten animals, and one control group of four animals. Two groups were inoculated with a single dose of either T. gondii tissue cysts or T. spiralis muscle larvae, one group was inoculated simultaneously with both parasites and two groups were successively inoculated at an interval of four weeks. Specific IgG responses to the parasites were measured by ELISA. T. gondii burden was determined by MC-PCR carried out on heart muscle and T. spiralis burden by artificial digestion of diaphragm samples. Specific IgG responses to T. gondii and T. spiralis in single and simultaneously inoculated animals showed a respective T. gondii and T. spiralis inoculation effect but no significant interaction of these parasites to the development of specific antibodies with the serum dilutions used. Moreover, our data showed that the specific IgG response levels in groups of animals successively or simultaneously co-infected were independent of a respective previous or simultaneous infection with the other parasite. Additionally, no differences in parasite burden were found within groups inoculated with T. gondii and within groups inoculated with T. spiralis. Conclusively, for the infection doses tested in this experiment, the dynamics of specific antibody development does not differ between single and simultaneous or successive infection with T. gondii and T. spiralis. However, lower parasitic doses and other ratios of doses, like low-low, low-high and high-low of T. gondii and T. spiralis in co-infection, in combination with other time intervals between successive infections may have different outcomes and should therefore be studied in further detail.

Evaluation of suspension array analysis for detection of egg yolk antibodies against Salmonella Enteritidis.

Salmonella enterica serovar Enteritidis (SE) is an important source of food-related diarrhoea in humans, and table eggs are considered the primordial source of contamination of the human food chain. Using eggs collected at egg-packing stations as samples could be a convenient strategy to detect colonization of layer flocks. The aim of this study was to evaluate egg yolk anti-Salmonella antibody detection using suspension array analysis. An egg yolk panel from contact-infected and non-colonized laying hens was used for the evaluation. Receiver Operating Characteristic (ROC) curves were generated to define a cut-off value and to assess the overall accuracy of the assay. The diagnostic sensitivity and specificity were estimated by maximum likelihood. Sensitivity was quantified on hen level and on sample level, and also quantified as a function of time since colonization. The area under the ROC curve was estimated at 0.984 (se 0.006, P<0.001). Of all colonized contact-infected hens, 67.6% [95% CI: 46.8, 100] developed an antibody response, which was detectable 17.4 days [14.3, 26.9] after colonization. In total, 98% [95.4, 99.4] of the 'immunopositive' hens had test positive eggs. The overall sensitivity of the immunological test was 66.7% [45.9, 98.7] and the specificity was 98.5% [97.8, 99.1]. This study provided essential parameters for optimizing surveillance programs based on detection of antibodies, and indicates that immunology based on examination of egg yolk gives important information about the Salmonella status of the flock.

Energy partitioning and thyroid hormone levels during Salmonella enteritidis infections in pullets with high or low residual feed intake.

This experiment was conducted to investigate whether feed efficiency, as measured by residual feed intake as a phenotypic trait, affects energy partitioning in pullets that have received Salmonella inoculation as an immune challenge. In each of 8 trials, energy partitioning was measured during 5 wk in 15-wk-old efficient (R-) and nonefficient (R+) pullets, which were housed per efficiency group in 2 identical climate respiration chambers. After 1 wk of adaptation, the pullets in 4 trials were orally inoculated with 10(8) cfu of Salmonella enteritidis; pullets in the remaining trials were not inoculated and served as controls. Heat production was calculated from continuous recordings of O(2) consumption and CO(2) production. Energy and N partitioning were recorded on a weekly basis. Blood samples for analyses on thyroid hormones were taken at 16, 17, and 19 wk of age. There were no interactions between efficiency type and Salmonella treatment or Salmonella treatment effects in energy partitioning, except for a short-term increase in heat production in inoculated pullets. Nonefficient pullets had higher gross energy and ME intake, higher estimated ME for maintenance, lower ME:gross energy ratio, and higher total heat production and nonactivity-related heat production compared with R- pullets. Triiodothyronine levels in R+ pullets were higher at 16 and 17 wk but were lower at 19 wk of age compared with R- pullets. Thyroxine levels were higher in R- at 16 wk and showed interactions between efficiency type and Salmonella treatment at 17 and 19 wk of age. Body weights and spleen weights did not differ between efficiency groups. Nonefficient pullets had higher heart, liver, and ovary weights and more large yellow follicles than R- pullets. There were no Salmonella effects on body and organ weights. We conclude that R+ pullets have a faster running energy metabolism and that they put more resources into organ development than R- pullets. Inoculation with Salmonella has a short-term effect on nonactivity-related heat production but does not affect energy partitioning, regardless of efficiency type.

Salmonella challenge affects the antibody isotype profile of bile in hens differing in metabolic efficiency.

Gel precipitation reactions determined antibody isotypes in bile from hens differing in dietary efficiency. Ouchterlony double diffusion employing alpha-chain specific goat-anti-chicken IgA, rabbit anti-chicken IgG, goat anti-chicken IgM, black turtle bean (BTB), and Jacalin lectins as precipitating reagents detected bile IgA, IgG, and IgM from Salmonella exposed and nonexposed hens. The IgA was present in 1 of 3 forms designated by reagent and frequency: IgAB (precipitated by BTB lectin) 100%; IgAA (precipitated by anti-alpha chain antibody) 98%, and IgAJ (precipitated by Jacalin) 97%. That both BTB and Jacalin precipitates contain IgA was confirmed by immuno-dot blots using affinity purified alpha-chain specific antibody, establishing each as IgA glycoforms. Three measurements of Ouchterlony precipitates were made; d1 and d2 indicate diffusion from sample or reagent wells, lambda indicates arc length. Mean values for lambda, estimating quantity, were IgAA (11.3 mm) and IgAB (11.6 mm) and IgAJ (8.3 mm). The crescent shape IgAJ arc and its slower diffusion (d1) suggested its molecular weight is greater than either IgAA or IgAB. Arc lengths of individual samples were not significantly correlated suggesting that these are independent components of bile. Oral Salmonella enteritidis challenge resulted in a highly significant difference in bile IgA profiles. The IgAJ arc lengths (lambda) in R- hens increased by 20% over those in nonchallenged R- hens. Conversely S. enteritidis challenge was associated with a decrease of 10% in IgAJ arc lengths in nonefficient (R+) hens. Salmonella enteritidis challenge was not associated with arc length differences in either IgAA or IgAB. The IgG was present in all specimens, and in 9 of 59 (15%) 2 forms were detected. The IgG quantity was unaffected by either efficiency type or S. enteritidis challenge. The IgM was detected in only 2 of 59 (3.4%) specimens. Our observations suggest IgA of bile is composed of multiple forms influenced both by diet efficiency status and S. enteritidis exposure. It appears that the latter resulted in an increased quantity of IgAJ in R- hens, and suggests the existence of functional differences among the various IgA types.

Natural anti-Gal and Salmonella-specific antibodies in bile and plasma of hens differing in diet efficiency.

Specific anti-Salmonella enteritidis (SE) and natural anti-alpha-gal epitope (Galalpha1-3Galbeta-1-4GlcNAc-R; anti-Gal) antibodies were measured in plasma sample pools and individual bile specimens obtained from hens differing in diet efficiency. More SE somatic (O) and flagellar (H) antibodies were found in plasma pools from efficient hens (R-) compared with nonefficient hens (R+) after oral challenge with live SE. Mean titers of somatic agglutinins in bile were 2.3 in R- hens and 1.9 in R+ hens (P = 0.06) following live challenge. Salmonella enteritidis antibodies were also found in bile of nonchallenged hens of both types but their levels were not significantly different. Flagellar (H) agglutinin scores were higher in SE-challenged hens compared with nonchallenged hens (3.1 vs. 2.1; P < or = 0.004) but efficiency types did not differ. Bile also contained high titers of the anti-Gal antibody indicated by the agglutination of glutaraldehyde-stabilized rabbit erythrocytes. The average titer of all SE-nonexposed hens was 9.0 corresponding to 1:5,120 when corrected for the initial dilution and expressed in conventional terms. Salmonella enteritidis exposure was associated with higher anti-Gal titers. The average anti-Gal titer for all SE-exposed hens was 10.0, corresponding to 1:10,240 in conventional terms; this difference was significant (P < or = 0.016). Diet efficiency type-associated differences in anti-Gal titers were not significant. Collectively, our data indicate that diet efficiency status is not associated with compromised Salmonella-specific immune responses. Rather it appears that the immune responses of diet efficient hens (R-) are also more efficient. This is because R- hens produced higher levels of O- and H-type antibody only as the result of direct exposure to living SE. On the contrary, R+ hens produced H-type antibody because of challenge with heat-killed SE, a circumstance that will not result in disease. Moreover, the hen type difference does not seem to occur at the expense of innate immunity as measured by anti-Gal antibody levels.

Residual feed intake and its effect on Salmonella enteritidis infection in growing layer hens.

Previous phenotypic selection on residual feed intake (RFI) identified 20 efficient R- chickens and 20 nonefficient R+ chickens. Residual feed intake was defined as the difference between observed feed intake (FI) and expected FI based on metabolic BW and BW gain, and was used as a measure for feed efficiency. Body weight and BW gain were similar for both groups. Feed intake and RFI were significantly higher in R+ birds. It is hypothesized that nonefficient R+ birds are more flexible to divert resources from production processes toward maintenance processes, thus being better capable of handling a bacterial challenge. Chickens of both groups were randomly allocated to immunization with heat-inactivated Salmonella enteritidis bacteria, or inoculation with live Salmonella bacteria. Transportation to the isolation units caused a decrease in FI in R+ birds. This may reflect a particular way of coping with stress in R+ birds. More R+ birds stopped bacterial shedding considering a nonshedding interval of 10 or 11 d (P = 0.041). Nonantigen-specific antibody responses against keyhole limpet hemocyanin (KLH) were higher in R- birds. We conclude that R+ birds are able to keep their metabolism at a higher level, as indicated by higher heart and liver weights, and that Salmonella infection leads to reduced heart, liver, and gizzard weights. Oviduct weight and number of small yellow follicles were reduced in infected birds. Antigen-specific antibody responses were not different between the groups, indicating high priority for this parameter as a life trait. Possible differences in stress susceptibility between efficient and nonefficient chickens need further examination.

Phenotypic selection for residual feed intake and its effect on humoral immune responses in growing layer hens.

According to the resource allocation theory, animals have to make a trade-off between resource-demanding life traits to obtain maximal fitness. Artificial selection toward efficient producing farm animals, however, may have created animals that have an impaired ability to divert resources to maintenance processes, such as responding to immune challenges. Residual feed intake (RFI), defined as the difference between observed feed intake (FI) and expected feed intake based on metabolic BW and growth, was used as a measure for feed efficiency. Individual BW and FI of 352 pullets were recorded weekly from 4 until 14 wk of age to estimate RFI. The top 50 efficient R- and the top 50 nonefficient R+ birds were selected. BW and BW gain in both groups were similar. FI and RFI, however, were significantly higher in R+ birds. Thirty animals out of every group were randomly allocated to 1 of 3 treatments: immunization with keyhole limpet hemocyanin (KLH), Mycobacterium butyricum, or heat-inactivated Salmonella enteritidis bacteria. Antibody titers against KLH, M. butyricum, or Salmonella lipopolysaccharide did not differ between R+ and R- birds. The antibody titer against Salmonella protein was higher in R+ birds. We concluded that a population of chickens from a commercial breed shows considerable variation in RFI. Specific antibody production against KLH, M. butyricum, and S. enteritidis lipopolysaccharide, however, is not influenced by efficiency in terms of RFI. R+ animals may have a higher level of nonantigen specific antibodies, as indicated by the higher antibody response to Salmonella protein.